Membrane technology has been studied in the past to produce polymer grade propylene. For example, there are inventions that relate to installing a membrane module at the overhead of the C3 splitter. Other innovations also investigated integrating membranes around the C3 splitter. However, the one column that cannot be eliminated with any combination of membranes is the C3/C4 splitter because the membrane cannot perform carbon number separation. Therefore, it is advantageous to leverage the C3/C4 splitter as much as possible to minimize the membrane section and overall cost. It is feasible to use a C3/C4 splitter in combination with membranes to produce polymer grade propylene.